AI Hallucination Cases

AI Use

The court observed that “some of the cases that plaintiff cites… do not exist,” and noted it had “tried, in vain,” to find them. While no explicit AI use is admitted by the plaintiff, the pattern and specificity of the fabricated citations are characteristic of LLM-generated hallucinations.

Ruling/Sanction

The court dismissed all five causes of action—including negligence, tortious interference, aiding and abetting fraud, declaratory judgment, and breach of implied covenant of good faith and fair dealing—as either untimely or duplicative/deficient on the merits. It declined to impose sanctions but explicitly invoked Dowlah v. Professional Staff Congress, 227 AD3d 609 (1st Dept. 2024), and Will of Samuel, 82 Misc 3d 616 (Sur. Ct. 2024), to warn plaintiff that any future citation of fictitious cases would result in sanctions.

Key Judicial Reasoning

Justice Jamieson noted that while the court is “sensitive to plaintiff's pro se status,” that does not excuse disregard of procedural rules or the submission of fictitious citations. The court emphasized that its prior decision in related litigation in 2022 undermined plaintiff’s tolling claims, and that Executive Order extensions during the COVID-19 pandemic did not rescue otherwise-expired claims. The hallucinated citations failed to salvage plaintiff’s fraud and tolling theories, and their use was treated as an aggravating—though not yet sanctionable—factor.

"For that principal [sic] [X] cites a case, Gunn v. McKinney, 259 F.3d 824, 829 (7th Cir. 2001), which neither defense counsel nor the Court has been able to locate. The Court reminds [X] that Federal Rule of Civil Procedure 11 applies to pro se litigants, and sanctions may result from such conduct, especially if the citation to Gunn was not merely a typographical or citation error but instead referred to a non-existent case. By presenting a pleading, written motion, or other paper to the Court, an unrepresented party acknowledges they will be held responsible for its contents. See Fed. R. Civ. P. 11(b)."

Court held that: "The use of fictitious quotes or cases in filings may subject a party, including a pro se party, to sanctions pursuant to Federal Rule of Civil Procedure 11 as “pro se litigants are subject to Rule 11 just as attorneys are.”

In their Response to the Order to show Cause, Counsel specified that they used Lexis+AI, and stressed that "LexisNexis itself has publicly emphasized the reliability of its Lexis+ AI platform, marketing it as providing “hallucination-free legal citations” specifically to avoid citation errors."
Case was eventually jointly dismissed.

The landlord sought to repossess a rental property, claiming the lease renewal was suspended based on a misinterpretation of Quebec's civil code articles. He used ChatGPT to translate these articles, which resulted in a completely different meaning. The Tribunal found the repossession request invalid as it was based on a date prior to the lease's end. The Tribunal rejected the claim of abuse, accepting the landlord's sincere belief in his misinterpretation, influenced by AI translation, and noted his language barrier and residence in Mexico. The Tribunal advised the landlord to seek reliable legal advice in the future.

AI Use

The court stated that “Moales may have used artificial intelligence in drafting his submissions,” citing widespread concerns over AI hallucination. It noted that several citations in his complaint and show-cause response were plainly incorrect or irrelevant. While Moales did not admit AI use, the court cited Strong v. Rushmore Loan Mgmt. Servs., 2025 WL 100904 (D. Neb.) and Mata v. Avianca to contextualize its concern.

Hallucination Details

Cited Ernst & Ernst v. Hochfelder, 425 U.S. 185 (1976), and S.E.C. v. W.J. Howey Co., 328 U.S. 293 (1946) as supporting the existence of a federal common law fiduciary duty—an inaccurate legal proposition. The court characterized such misuses as “the norm rather than the exception” in Moales’s submissions. It stopped short of identifying all misused authorities but made clear that the inaccuracies were pervasive.

Ruling/Sanction

The complaint was dismissed for lack of subject matter jurisdiction under Rule 12(h)(3). Moales was permitted to file an amended complaint by May 28, 2025, but was warned that future filings must be factually and legally accurate. The court declined to reach the venue issue or impose immediate sanctions but warned Moales that misrepresentation of law may violate Rule 11.

Key Judicial Reasoning

The court found no basis for federal question jurisdiction and rejected Moales’s reliance on the Declaratory Judgment Act, constructive trust theories, and a nonexistent “federal common law of securities.” It also held that Moales failed to plausibly allege the amount in controversy necessary for diversity jurisdiction.

AI Use

Counsel denied using AI directly and attributed the hallucinations to “Google and Google Scholar” searches by a junior research assistant. However, the court found the citation pattern highly characteristic of generative AI hallucinations, including plausible-sounding but non-existent authority names and improper formatting. Counsel acknowledged a lack of adequate supervision and admitted that the cited authorities were never verified nor included in the bundle.

Hallucination Details

Seven cited authorities were found to be fictitious or mischaracterized, including:

• BWIA v. Ramnarine (TT Industrial Court, 2005)
• National Petroleum Marketing Co. v. Brewster (TT 2007)
• Horner v. KMW [2000] IRLR 814
• Jones v. Manchester Corporation [1952] 2 QB 852 (used for unrelated point)
• London School of Economics v. Dr Don [2016] EAT
• Ishmael v. NIPDEC (TT, 2014)
• BWIA v. Hollis (TT, 2001)

These were used to support the implied obligation to repay employer-sponsored training, the core issue of the case. None were available in legal databases or official archives, and no hard copies were ever submitted.

Ruling/Sanction

While the court awarded judgment for the Claimant on the breach of contract claim, it found the citation misconduct egregious and referred the matter to the Disciplinary Committee of the Law Association. The Court noted that hallucinated citations undermine judicial integrity and must be proactively prevented.

Key Judicial Reasoning

Justice Westmin James emphasized that lawyers must not submit unverifiable or fictitious authority, whether generated by AI or not. He underscored that the legal system depends on the accuracy of submissions, and that even unintentional use of hallucinated material violates the duty of candour and may constitute professional misconduct.

AI Use

The plaintiff’s attorney denied deliberate use of generative AI, claiming the wrong file numbers were inserted by mistake. The court rejected this explanation, finding the hallucinated decisions did not exist in any legal archive and could not plausibly arise from mere misnumbering. The court accepted the defendant’s assertion that the fabricated citations originated from generative AI.

Hallucination Details

Out of five rulings cited in the petition, three were not found in any legal database. Two additional cases were filed after the hearing, but neither matched the original citations or contained the propositions advanced in the pleading. The court found the overall drafting pattern aligned with generative AI hallucination phenomena.

Ruling/Sanction

Judge Merav Eliyahu dismissed the petition and imposed personal costs of ₪1,500 against Plaintiff’s counsel (payable to the state) and ₪3,500 (payable to the opposing party). She cited Supreme Court precedent and ethical commentary emphasizing the risks of hallucinated legal drafting. She emphasized that lawyers must not rely blindly on AI tools and must always verify the authenticity of legal authorities cited in pleadings.

Key Judicial Reasoning

The judge found that legal pleadings are the “foundational documents of judicial proceedings” and must be “accurate, reliable, and competently drafted.” Submitting fictitious judgments constitutes not only a procedural abuse but an ethical breach. Even absent bad faith, failure to verify AI-generated legal content breaches a lawyer’s core obligations.

"Ms. Simpson referred to a non-existent CRT case to support a patently incorrect legal position. She also referred to three Supreme Court of Canada cases that do not exist. Her submissions go on to explain in detail what legal principles those non-existent cases stand for. Despite these deficiencies, the submissions are written in a convincingly legal tone. Simply put, they read like a lawyer wrote them even though the underlying legal analysis is often wrong. These are all common features of submissions generated by artificial intelligence." [...]

"25. I agree with Hung Long that there are two extraordinary circumstances here that justify compensation for its time. The first is Ms. Simpson’s use of artificial intelligence. It takes little time to have a large language model create lengthy submissions with many case citations. It takes considerably more effort for the other party to wade through those submissions to determine which cases are real, and for those that are, whether they actually say what Ms. Simpson purported they did. Hung Long’s owner clearly struggled to understand Ms. Simpson’s submissions, and his legal research to try to understand them was an utter waste of his time. I reiterate my point above that Ms. Simpson’s submissions cited a non-existent case in support of a legal position that is the precise opposite of the existing law. This underscores the impact on Hung Long. How can a self-represented party respond to a seemingly convincing legal argument that is based on a case it is impossible to find?

26. I am mindful that Ms. Simpson is not a lawyer and that legal research is challenging. That said, she is responsible for the information she provides the CRT. I find it manifestly unfair that the burden of Ms. Simpson’s use of artificial intelligence should fall to Hung Long’s owner, who tried his best to understand submissions that were not capable of being understood. While I accept that Ms. Simpson did not knowingly provide fake cases or misleading submissions, she was reckless about their accuracy."

AI Use

Counsel used ChatOn to rewrite a reply brief with case law, under time pressure, without verifying the outputs. The five cases did not exist; citations were entirely fictional. Counsel later admitted this in a sworn declaration and at hearing, describing her actions as a lapse caused by workload and inexperience with AI.

Hallucination Details

Fabricated cases included:

• Klein v. E.I. Du Pont de Nemours & Co., 406 F.2d 1004 (cited case does not exist)
• Gordon v. N.Y. Cent. R.R. Co., 202 F. Supp. 2d 290
• Mitchell v. JCG Industries, 2010 WL 11627832
• Hollander v. Sweeney, 2005 WL 19904045
• Davis v. S. Farm Bureau Cas. Ins. Co., 2019 WL 3452601

None of these cases matched any legal source. Counsel filed them as part of a sworn statement under penalty of perjury.

Ruling/Sanction

The court imposed a $1,000 sanction payable to the Clerk; ordered the counsel to serve the order on her client and file proof of service. The court acknowledged her sincere remorse and remedial CLE activity, but emphasized the seriousness of submitting hallucinated cases under oath. Sanctions were tailored for deterrence, not punishment.

Key Judicial Reasoning

Quoting Park v. Kim and Mata v. Avianca, the court held that submitting legal claims based on nonexistent authorities without checking them constitutes subjective bad faith. Signing a sworn filing without knowledge of its truth is independently sanctionable. Time pressure is not a defense. Lawyers cannot outsource core duties to generative AI and disclaim responsibility for the results.

Solution upheld on appeal (see here).

Although no immediate sanctions were imposed, Magistrate Judge Ho explicitly warned Plaintiff that future misconduct of this nature may violate Rule 11 and lead to consequences.

AI Use

Mr. Ferris admitted at the April 8, 2025 hearing that he used ChatGPT to generate the legal content of his filings and even the statement he read aloud in court. The filings included at least seven entirely fictitious case citations. The court noted the imbalance: it takes a click to generate AI content but substantial time and labor for courts and opposing counsel to uncover the fabrications.

Hallucination Details

The hallucinated cases included federal circuit and district court decisions, complete with plausible citations and jurisdictional diversity, crafted to lend credibility to Plaintiff’s intellectual property and employment-related claims. These false authorities were submitted both in the complaint and in opposition to Amazon’s motion to dismiss.

Ruling/Sanction

The court found a Rule 11 violation and, while initially inclined to dismiss the case outright, chose instead to impose a compensatory monetary sanction. Amazon is entitled to submit a detailed affidavit of costs directly attributable to rebutting the false citations. The final monetary amount will be set in a subsequent order.

Key Judicial Reasoning

Judge Michael P. Mills condemned the misuse of generative AI as a serious threat to judicial integrity. Quoting Kafka (“The lie made into the rule of the world”), the court lamented the rise of “a post-truth world” and framed Ferris as an “avatar” of that dynamic. Nevertheless, it opted for the least severe sanction consistent with deterrence and fairness: compensatory costs under Rule 11.

After explaining what happened (document) counsel opted to non-suit all remaining claims, which means that the court never ruled on the show cause proceedings.

AI Use

Counsel filed opposition briefs citing two nonexistent cases. The court suspected generative AI use based on "hallucination" patterns but Counsel neither admitted nor explained the citations satisfactorily. Failure to comply with a standing AI order aggravated sanctions.

Hallucination Details

Two fake cases cited. Citation numbers and Westlaw references pointed to irrelevant or unrelated cases. No affidavit or real case documents were produced when ordered.

Ruling/Sanction

Counsel's appearance was struck with prejudice. The Court ordered notification to the State Bar of Pennsylvania and the Eastern District Bar. Consel was required to inform his client, Bevins, of the sanctions and the need for new counsel if re-filing.

The court held that: "It is likely that Appellant employed argument generated by an artificial intelligence (AI) program which contained the fictitious case citation and cautions Appellant that many harms flow from the use of non-existent case citations and fake legal authority generated by AI programs, including but not limited to the waste of judicial resources and time and waste of resources and time of the opposing party. Were courts to unknowingly rely upon fictitious citations, citizens and future litigants might question the validity of court decisions and the reputation of judges. If, alternatively, Appellant's use of a fictitious case was not the result of using an AI program, but was instead a conscious act of the Appellant, Appellant's action could be deemed a fraud on the Court. Appellant is hereby expressly warned that submission of fictitious case authorities may subject Appellant to sanctions under the S.C. Frivolous Proceedings Act, S.C. Code Ann. § 15-36-10(Supp. 2024)."

AI Use

The judgment states that the only other explanation for the fabricated cases was the use of artificial intelligence.

Hallucination Details

The following five nonexistent cases were cited:

• R (El Gendi) v Camden [2020] EWHC 2435 (Admin)
• R (Ibrahim) v Waltham Forest [2019] EWHC 1873
• R (H) v Ealing [2021] EWHC 939 (Admin)
• R (KN) v Barnet [2020] EWHC 1066 (Admin)
• R (Balogun) v Lambeth [2020] EWCA Civ. 1442

Ruling/Sanction

The court imposed wasted costs orders against both barrister and solicitor, reduced the claimant’s recoverable costs, and ordered the judgment to be provided to the BSB and SRA.

AI Use

The petitioner submitted a motion to compel discovery that contained several fabricated or misleading citations. The court explicitly stated that the motion bore hallmarks of generative AI use and referenced ChatGPT’s known risk of “hallucinations.” Although the petitioner did not admit AI use, the court found the origin clear and required future filings to include a GenAI usage certification.

Hallucination Details

Examples included:

• Terramar Retail Centers, LLC v. Marion #2-Seaport Trust – cited for discovery principles it did not contain
• Deutsch v. ZST Digital Networks, Inc. – quoted for a sentence not found in the opinion
• Production Resources Group, LLC v. NCT Group, Inc. – attributed with a quote that appears nowhere in the case or legal databases

Court verified via Westlaw that some phrases returned only the petitioner’s motion as a result.

Ruling/Sanction

Motion to compel denied with prejudice. No immediate monetary sanction imposed, but petitioner was warned that further submission of fabricated authority may result in sanctions including monetary penalties or dismissal. Future filings must include a certification regarding the use of generative AI.

Key Judicial Reasoning

The Vice Chancellor emphasized that GenAI can benefit courts and litigants, but careless use that results in fictitious legal authorities wastes resources and harms judicial integrity.

Plaintiff had disclosed the use of AI in preparing his statement of case. The court noted:

"29. However, our conclusion was that Mr Zzaman’s statement of case, written with the assistance of AI, did not provide grounds for allowing his appeal. Although some of the case citations in Mr Zzaman’s statement were inaccurate, the use of AI did not appear to have led to the citing of fictitious cases (in contrast to what had happened in Felicity Harber v HMRC [2023] UKFTT 1007 (TC)). But our conclusion was that the cases cited did not provide authority for the propositions that were advanced. This highlights the dangers of reliance on AI tools without human checks to confirm that assertions the tool is generating are accurate.

Litigants using AI tools for legal research would be well advised to check carefully what it produces and any authorities that are referenced. These tools may not have access to the authorities required to produce an accurate answer, may not fully “understand” what is being asked or may miss relevant materials. When this happens, AI tools may produce an answer that seems plausible, but which is not accurate. These tools may create fake authorities (as seemed to be the case in Harber) or use the names of cases to which it does have access but which are not relevant to the answer being sought (as was the case in this appeal).

There is no reliable way to stop this, but the dangers can be reduced by the use of clear prompts, asking the tool to cite specific paragraphs of authorities (so that it is easy to check if the paragraphs support the argument advanced), checking to see the tool has access to live internet data, asking the tool not to provide an answer if it is not sure and asking the tool for information on the shortcomings of the case being advanced. Otherwise there is a significant danger that the use of an AI tool may lead to material being put before the court that serves no one well, since it raises the expectations of litigants and wastes the court’s time and that of opposing parties."

Alan Hood relied on an AI search that inferred the Council was required to notify objectors. The Tribunal found that inference 'plainly incorrect', noting Hood had received the requisite notice and should have read the documents; the Tribunal nevertheless exercised discretion to join him.

AI Use

Counsel hired a freelance attorney through LAWCLERK to prepare a filing. He made minimal edits and admitted not verifying any of the case law before signing. The filing included multiple fabricated cases and misquoted others. The court concluded these were AI hallucinations, likely produced by ChatGPT or similar.

Hallucination Details

Examples of non-existent cases cited include:

Moncada v. Ruiz, Vega-Mendoza v. Homeland Security, Morales v. ICE Field Office Director, Meza v. United States Attorney General, Hernandez v. Sessions, and Ramirez v. DHS.

All were either entirely fictitious or misquoted real decisions.

Ruling/Sanction

The Court sanctioned Counsel by:

• Ordering a $1,500 fine
• Requiring a 1-hour CLE on AI/legal ethics
• Ordering him to self-report to the New Mexico and Texas bars
• Ordering him to report the freelance lawyer to the New York bar
• Requiring notification of LAWCLERK
• Requiring proof of compliance by May 15, 2025

Key Judicial Reasoning

The court emphasized that counsel’s failure to verify cited cases, coupled with blind reliance on subcontracted work, constituted a violation of Rule 11(b)(2). The court analogized to other AI-sanctions cases. While the fine was modest, the court imposed significant procedural obligations to ensure deterrence.

AI Use

The plaintiff did not admit to using AI, but the court inferred likely use due to the submission of fabricated citations matching the structure and behavior typical of generative AI hallucinations. The decision referenced public concerns about AI misuse and cited specific examples of federal cases where similar misconduct occurred.

Hallucination Details

Plaintiff cited:

• Tucker v. United States, 24 Cl. Ct. 536 (1991) – does not exist
• Fargo v. United States, 184 F.3d 1096 (Fed. Cir. 1999) – fabricated citation pointing to an unrelated Ninth Circuit case
• Bristol Bay Native Corporation v. United States, 87 Fed. Cl. 122 (2009) – fictional
• Quantum Construction, Inc. v. United States, 54 Fed. Cl. 432 (2002) – nonexistent
• Hunt Building Co., LLC v. United States, 61 Fed. Cl. 243 (2004) – real case misused; contains no mention of unjust enrichment

Ruling/Sanction

The court granted the government’s motion to dismiss for lack of subject matter jurisdiction under Rule 12(b)(1). Although the court found a clear Rule 11 violation, it opted not to sanction the plaintiff, citing the evolving context of AI use and the absence of bad faith. A formal warning was issued, with notice that future hallucinated filings may trigger sanctions.

Key Judicial Reasoning

Judge Roumel noted that plaintiff’s attempt to rely on fictional case law was a misuse of judicial resources and a disservice to her own advocacy. The court cited multiple precedents addressing hallucinated citations and AI misuse, stating clearly that while leeway is granted to pro se litigants, the line is crossed when filings rely on fictitious law.

AI Use

Although AI was not named and Plaintiff denied intentional fabrication, the court considered the citation (Adamov, 779 F.3d 851, 860 (8th Cir. 2015)) to be plainly fictitious. It noted the possibility that Plaintiff used generative AI tools, given the fabricated citation's plausible-sounding structure and mismatch with existing precedent.

Hallucination Details

Plaintiff submitted fabricated legal authorities in at least two filings, despite being explicitly warned by the court after the first incident. The false case cited in her sur-reply could not be located in any legal database. When asked to produce it, she responded that she had likely “garbled” the citation but provided no plausible alternative or correction.

Ruling/Sanction

The court declined to dismiss the action as a sanction, citing the limitations pro se litigants face in accessing reliable legal research tools. However, it granted the defendant’s motion to strike Plaintiff’s two unauthorized sur-replies and formally warned her that further violations of Rule 11 would lead to sanctions, including monetary penalties, filing restrictions, or dismissal.

"By relying on inaccurate and false AI submissions, Mr. Oak hurts his own case. I understand that Mr. Oak himself might not be aware that the submissions are misleading, but they are his submissions and he is responsible for them. "

AI Use

The applicant cited Crime and Misconduct Commission v Chapman [2007] QCA 283 in support of a key submission. The Tribunal was unable to locate such a case. It queried ChatGPT, which returned a detailed but entirely fictitious account of a case that does not exist. The Tribunal attached Queensland’s AI usage guidelines to its reasons and emphasized that the responsibility for accuracy lies with the party submitting the material.

Ruling/Sanction

The fabricated case was disregarded. The Tribunal granted a stay but issued a strong warning: litigants are responsible for understanding the limitations of AI tools and must verify all submitted material. The inclusion of fictitious material wastes time, diminishes credibility, and undermines the process.

Key Judicial Reasoning

Citing non-existent authorities "weakens their arguments. It raises issues about whether their submission can be considered as accurate and reliable. It may cause the Tribunal to be less trusting of other submissions which they make. It wastes the time for Tribunal members in checking and addressing these hallucinations. It causes a significant waste of public resources."

AI Use

Kruglyak acknowledged he had used free generative AI tools to conduct legal research and included fabricated case citations and misrepresented holdings in his filings. He claimed ignorance of AI hallucination risk at the time of filing but stated he had since ceased such reliance and sought more reliable legal sources.

Hallucination Details

The plaintiff cited non-existent decisions and falsely attributed holdings to real ones. He did not initially disclose the use of AI but conceded it in response to the court’s show cause order. The brief at issue combined wholly fabricated cases with distorted summaries of actual ones.

Ruling/Sanction

Magistrate Judge Sargent concluded that Kruglyak had not acted in bad faith, credited his prompt admission and explanation, and noted his subsequent remedial efforts. No monetary sanctions were imposed, but the court emphasized its authority to impose such penalties if future violations occur.

Key Judicial Reasoning

The court stressed that while generative AI platforms may assist litigants, they are unreliable legal authorities prone to hallucinations. Rule 11 requires a reasonable inquiry before filing, and ignorance of AI limitations does not excuse defective legal submissions. However, leniency was warranted here due to Kruglyak’s candor and corrective action.

In a subsequent Order, the court pointed out that "This Court's opinion pointing out Buckner's citation to nonexistent case law, along with its implications, is an issue for appeal and not a valid basis for recusal. "

AI Use

While not formally admitted, Plaintiff’s opposition brief referred to “legal generative AI program CoCounsel,” and the court noted that the structure and citation pattern were consistent with AI-generated output. Capital One was unable to verify several case citations, prompting the court to scrutinize the submission.

Hallucination Details

At least one case was fully fabricated, and another was a real case misattributed to the wrong jurisdiction and reporter. The court emphasized that it could not determine whether the mis-citations were the result of confusion, poor research, or hallucinated AI output—but the burden rested with the party filing them.

Ruling/Sanction

The court dismissed the complaint with prejudice, noting Plaintiff had already filed and withdrawn a prior version and had had full opportunity to amend. Though it did not impose monetary sanctions, it issued a strong warning and directed Plaintiff to notify other courts where he had similar pending cases if any filings included erroneous AI-generated citations.

AI Use

Justice Nolan suspected that Reddan's submissions, especially references to "subornation to perjury" and Constitutional Article 40 rights, were AI-generated, exhibiting typical hallucination patterns (pseudo-legal concepts, inappropriate cut-and-paste fragments). Reddan did not admit using AI but relied on internet-sourced legal arguments that closely resembled LLM-style outputs.

Hallucination Details

Inappropriate invocation of "subornation to perjury," a term foreign to Irish law. Constitutional and criminal law citations (Article 40, Non-Fatal Offences Against the Person Act) irrelevant to judicial review context. Assertions framed in hyperbolic, sensationalist terms without factual or legal basis. General incoherence of pleadings, consistent with AI-generated pseudo-legal text

Ruling/Sanction

The High Court refused leave to apply for judicial review on all nine grounds. While no formal financial sanction was imposed, Justice Nolan issued a sharp rebuke, highlighting the improper use of AI and warning against making scurrilous, unverified allegations in legal pleadings. The Court stressed that misuse of AI-generated material could itself amount to an abuse of the judicial process.